Many cameras have a built in flash unit. The flash unit is often located close to the optical axis of the camera lens. When the flash is located in the above position, flash from this position often results in unflattering illumination of the subject. Sometimes, the flash even enters the pupil of the eye of the subject and produces a condition called red eye. Red eye is caused by the reflection of the flash from the blood vessels in the retina, which is reflected back into the camera as red light. When the flash unit is raised above the lens, the condition called red eye is removed.
The close association of flash unit and camera, even without red eye gives a rather uninteresting, flat form of lighting, which does not suit many subjects. To obtain more diffuse, softer lighting and hence better pictures the reflector assembly of the flash unit can be swivelled or tilted to produce a bounce flash.
The typical bounce flash technique is to aim the flash unit at the ceiling, which then becomes a broad source of diffuse illumination, overcoming problems of light fall-off. If the flash unit has a provision for tilting, it can be used on a camera, if not it must be hand-held or mounted on some fixed support.
Current camera systems typically include a flash unit for low light situations. The flash unit consists of a flash tube and a reflector that are designed to illuminate the scene area captured by the lens of the camera. When the shutter of the camera is opened, a capacitor discharges through the flash tube to create a burst of light. A large number of people would rather carry a smaller camera instead of a larger camera. Thus, the flash unit was made part of the camera to reduce the number of objects that an individual would have to carry and the flash unit was reduced in size to reduce the size of the camera. Hence, flash units on current small camera typically have a range of twelve feet. Larger flash units that supply greater illumination are not typically a part of small cameras or exist as independent flash units.
When a bounce flash is utilized, the effective flash range of the flash unit is reduced by approximately two stops and bounce flash for a 12 foot flash range may be reduced to less than 8 feet. The foregoing may be overcome, by increasing the aperture size of the camera.
Studies have shown that people desire to take pictures of objects that are located as close as 21/2 feet from the camera. Cameras that are equipped with an autofocus feature sense the distance of the object and the accordingly set the focus of the lens to the subject distance. Cameras that incorporate the foregoing autofocus feature are more expensive than conventional cameras. As the aperture size of a camera lens increases the depth of field decreases, consequentially increasing the desirability of a autofocus feature.
In moderately priced cameras it is advantageous to have a single focus point for the lens. When a bounce flash is added to a moderately priced camera, the flash range of the bounce flash unit is reduced making the bounce flash unit useful only in a close up mode. The foregoing necessitates a focus shift of the lens. The prior art discloses either sophisticated adjustments in exposure and/or lens focus to optimize picture quality. Prior systems that utilized optimized flash bounce use autofocus technology.